[BlobAsync] Disk support for blob storage

storage/browser/blob/blob_memory_controller.h

+// Copyright 2016 The Chromium Authors. All rihts reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef STORAGE_BROWSER_BLOB_BLOB_MEMORY_CONTROLLER_H_
+#define STORAGE_BROWSER_BLOB_BLOB_MEMORY_CONTROLLER_H_
+
+#include <stdint.h>
+
+#include <algorithm>
+#include <list>
+#include <map>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/callback.h"
+#include "base/containers/mru_cache.h"
+#include "base/files/file.h"
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/optional.h"
+#include "base/time/time.h"
+#include "storage/browser/storage_browser_export.h"
+#include "storage/common/blob_storage/blob_storage_constants.h"
+#include "storage/common/data_element.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
+
+namespace storage {
+class ShareableBlobDataItem;
+class ShareableFileReference;
+
+// There should be no memory sizes of 0.
+// This class is responsible for
+// * our current memory usage for blobs, both on disk and in memory,
+// * when we can add a blob w/ a given size,
+// * creating temporary files,
+// * paging blobs to disk.
+class STORAGE_EXPORT BlobMemoryController
+    : public base::SupportsWeakPtr<BlobMemoryController> {
+ public:
+  enum class MemoryStrategyResult {
+    // We don't have enough memory for this blob.
+    TOO_LARGE,
+    // There isn't any memory that needs transporting.
+    NONE_NEEDED,
+    // Transportation strategies.
+    SHORTCUT,
+    IPC,
+    SHARED_MEMORY,
+    FILE
+  };
+  typedef std::list<std::pair<size_t, base::Callback<void(bool)>>>
+      PendingBlobConstructionList;
+  typedef PendingBlobConstructionList::iterator PendingContructionEntry;
+
+  struct FileCreationInfo {
+    FileCreationInfo();
+    ~FileCreationInfo();
+    FileCreationInfo(FileCreationInfo&& other);
+    FileCreationInfo& operator=(FileCreationInfo&&);
+
+    base::File::Error error = base::File::FILE_ERROR_FAILED;
+    scoped_refptr<ShareableFileReference> file_reference;
+    base::Optional<base::File> file = base::nullopt;

[kinuko, 2016/07/07 16:11:44]

base::File has invalid/empty status, is using Optional still that useful in this
case?

[michaeln, 2016/07/07 20:05:23]

The base::File object is inexpensive to construct and supports an empty state,
see the IsValid() method. I'm not so familiar with the Optional<> template or
when it's appropriate to use, it doesn't seem necessary in this case.

What the reason to use Optional<> for this data member?

[dmurph, 2016/07/11 23:33:27]

We don't always need it. Changed back to regular file.

+    base::Time last_modified;
+  };
+
+  BlobMemoryController();
+  virtual ~BlobMemoryController();
+
+  void SetMemoryLimits(size_t max_blob_in_memory_size_bytes,

[kinuko, 2016/07/07 16:11:44]

Do we need this in addition to / separately from SetMemoryContantsForTesting? 
This also seems to be used only for testing?

[dmurph, 2016/07/11 23:33:27]

Done.

+                       size_t max_blob_memory_space_bytes,
+                       uint64_t max_blob_disk_space_bytes,
+                       size_t in_flight_space_bytes,
+                       uint64_t min_page_file_size) {
+    max_blob_in_memory_size_ = max_blob_in_memory_size_bytes;
+    max_blob_memory_space_ = max_blob_memory_space_bytes;
+    max_blob_disk_space_ = max_blob_disk_space_bytes;
+    in_flight_space_ = in_flight_space_bytes;
+    min_page_file_size_ = min_page_file_size;
+  }
+
+  void EnableDisk(const base::FilePath storage_directory,

[kinuko, 2016/07/07 16:11:44]

nit: const ref?

[dmurph, 2016/07/11 23:33:27]

Done.

+                  scoped_refptr<base::SingleThreadTaskRunner> file_runner);
+
+  // Returns if the data in the descriptions is good data (not a bad IPC). If
+  // SHORTCUT is returned, then the blob can be immediately constructed, and
+  // the a following call to MaybeFitInMemoryNow will always return true.
+  bool DecideBlobTransportationMemoryStrategy(
+      const std::vector<DataElement>& descriptions,
+      uint64_t* total_bytes,
+      MemoryStrategyResult* result) const;
+
+  // Creates a temporary file that we store in our blob temporary directory. The
+  // lifetime of the file is tied to the file_reference.
+  void CreateTemporaryFileForRenderer(
+      uint64_t size_bytes,
+      const base::Callback<void(FileCreationInfo)>& done);
+
+  void FreeMemory(size_t memory_size_bytes);
+
+  enum class MemoryRequestResponse {
+    SPACE_AVAILABLE,
+    SPACE_UNAVAILABLE,
+    PENDING_DISK
+  };
+
+  bool CanFitInSystem(uint64_t size) const;
+
+  // We assume the user called CanFitInSystem before this and that the given
+  // memory size can fit in our system.
+  // Notifies the caller when a blob of the given size can be stored in our blob
+  // system. If the returned entry is not present, that means the blob can fit
+  // right away and the callback won't be called.
+  // The argument on can_request is true if we can create the blob, and
+  // false if there was an error and the new blob needs to be broken.
+  base::Optional<PendingContructionEntry> NotifyWhenMemoryCanPopulated(
+      size_t memory_size_bytes,
+      const base::Callback<void(bool)>& can_request);
+
+  void RemovePendingConstructionEntry(const PendingContructionEntry& entry);
+
+  // This updates the given item in our LRU lookup table.
+  void UpdateBlobItemInRecents(ShareableBlobDataItem* item);
+
+  // This removes the given item from our LRU lookup table.
+  void RemoveBlobItemInRecents(uint64_t id);

[michaeln, 2016/07/07 20:05:23]

for symmetry, maybe have this method take the |item| ptr as input like the
Update method does

[dmurph, 2016/07/11 23:33:27]

Done.

+
+  // Disables the disk.
+  void DisableDisk();

[kinuko, 2016/07/07 16:11:44]

nit: I feel this and disk_enabled() should be placed next to EnableDisk()

[dmurph, 2016/07/11 23:33:27]

Done.

+
+  bool disk_enabled() const { return disk_used_; }
+
+  size_t max_ipc_memory_size() const { return max_ipc_memory_size_; }
+  size_t max_shared_memory_size() const { return max_shared_memory_size_; }
+  size_t max_blob_in_memory_size() const { return max_blob_in_memory_size_; }
+  size_t max_blob_memory_space() const { return max_blob_memory_space_; }
+  uint64_t max_blob_disk_space() const { return max_blob_disk_space_; }
+  size_t in_flight_space() const { return in_flight_space_; }
+  uint64_t min_page_file_size() const { return min_page_file_size_; }
+  uint64_t max_file_size() const { return max_file_size_; }
+
+  void SetMemoryContantsForTesting(size_t max_ipc_memory_size,
+                                   size_t max_shared_memory_size,
+                                   size_t max_blob_in_memory_size,
+                                   size_t max_blob_memory_space,
+                                   uint64_t max_blob_disk_space,
+                                   size_t in_flight_space,
+                                   uint64_t min_page_file_size,
+                                   uint64_t max_file_size) {
+    max_ipc_memory_size_ = max_ipc_memory_size;
+    max_shared_memory_size_ = max_shared_memory_size;
+    max_blob_in_memory_size_ = max_blob_in_memory_size;
+    max_blob_memory_space_ = max_blob_memory_space;
+    max_blob_disk_space_ = max_blob_disk_space;
+    in_flight_space_ = in_flight_space;
+    min_page_file_size_ = min_page_file_size;
+    max_file_size_ = max_file_size;
+  }
+
+ private:
+  using RecentItemsCache = base::MRUCache<uint64_t, ShareableBlobDataItem*>;
+
+  // We add a delete callback to the file reference to decrement our disk usage.
+  void OnCreateFile(uint64_t file_size,
+                    const base::Callback<void(FileCreationInfo)>& done,
+                    FileCreationInfo result);
+
+  void MaybeScheduleWaitingBlobs();
+
+  // Returns the size we'll be freeing. We appropriately increment/decrement
+  // the disk, memory, and in flight counts.
+  size_t ScheduleBlobPaging();
+  void SchedulePagingUntilWeCanFit(size_t total_memory_needed);
+
+  // Called when we've completed paging a list of items
+  void OnPagingComplete(
+      std::unique_ptr<std::vector<scoped_refptr<ShareableBlobDataItem>>> items,
+      size_t total_items_size,
+      FileCreationInfo result);
+
+  void RecordTracingCounters();
+
+  size_t GetAvailableMemoryForBlobs() const;
+  uint64_t GetAvailableDiskSpaceForBlobs() const;
+
+  // We decrement the disk space used.
+  void OnBlobFileDelete(uint64_t size, const base::FilePath& path);
+
+  // Memory bookkeeping.
+  size_t blob_memory_used_ = 0;
+  size_t in_flight_memory_used_ = 0;
+  uint64_t disk_used_ = 0;
+
+  scoped_refptr<base::SingleThreadTaskRunner> file_runner_;
+
+  PendingBlobConstructionList blobs_waiting_for_paging_;
+  size_t blobs_waiting_for_paging_size_ = 0;
+
+  // Constants.
+  size_t max_ipc_memory_size_ = kBlobStorageIPCThresholdBytes;
+  size_t max_shared_memory_size_ = kBlobStorageMaxSharedMemoryBytes;
+  size_t max_blob_in_memory_size_ = kBlobStorageMaxBlobMemorySize;
+  size_t max_blob_memory_space_ = kBlobStorageMaxMemoryUsage;
+  uint64_t max_blob_disk_space_ = kBlobStorageMaxDiskSpace;
+  size_t in_flight_space_ = kBlobStorageInFlightMemory;
+  uint64_t min_page_file_size_ = kBlobStorageMinFileSizeBytes;
+  uint64_t max_file_size_ = kBlobStorageMaxFileSizeBytes;
+
+  bool enable_disk_ = false;
+  base::FilePath blob_storage_dir_;
+  uint64_t current_file_num_ = 0;
+
+  // Lifetime of the ShareableBlobDataItem objects is handles externally in the
+  // BlobStorageContext class.
+  RecentItemsCache recent_item_cache_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlobMemoryController);
+};
+}  // namespace storage
+#endif  // STORAGE_BROWSER_BLOB_BLOB_MEMORY_CONTROLLER_H_